High-viscosity ophthalmic compositions are useful for lengthening the residence times of compositions on the ocular surface thereby providing a sustained drug effect and preventing dry eye. Known thickening agents that are added to such high-viscosity ophthalmic compositions include cellulose-based polymers such as hypromellose, hydroxyethylcellulose and methylcellulose and vinyl-based polymers such as polyvinylpyrrolidone and polyvinyl alcohol and acrylic acid polymers such as carboxyvinyl polymer. Of these, carboxyvinyl polymers have a higher thickening effect than cellulose-based polymers that are widely used as components of an eye drop composition, and allow viscosities of several thousand to several tens of thousands mPa·s to be achieved even when used in small amounts, and they therefore serve as useful thickening agents.
Ophthalmic compositions such as an eye drop composition are generally housed and used in a container designed so that droplets can be dropped from an extraction opening (nozzle), by applying pressing force on the container. Modifications for dropping an eye drop composition from nozzles are therefore being devised.
For example, methods for improving liquid drip of an eye drop composition include the method described in Patent document 1 in which the material and shape of the nozzle are modified, but this method increases cost while also being limited to specific nozzle shapes, while it also places restrictions on the container shapes.
One method for dealing with poor liquid drip of an eye drop composition from nozzles is a method in which the nozzle is wiped with a clean wiper after each drip, in order to prevent deposition of the components, but this method not only fails to improve the liquid drip itself, but also increases inconvenience to the user. Also, Patent document 2 discloses a method of inhibiting deposition of components by addition of specific components into the liquid composition, but this method does not improve the liquid drip itself.
Addition of refrigerants such as menthol, camphor and borneol to ophthalmic compositions is already known. These refrigerants are known to impart a refreshing feel, while also exhibiting effects of alleviating ophthalmalgia induced by components (Patent document 3) and effects of improving the wettability of contact lenses (Patent document 4).
Addition of water-soluble polymers to ophthalmic compositions, in addition to refrigerants such as menthol, camphor and borneol, is also known. Such ophthalmic compositions are known to exhibit effects of improving the wettability of contact lenses (Patent documents 5 and 6), inhibiting adsorption of components onto contact lenses (Patent documents 7 and 8), maintaining a refreshing feel (Patent document 9), and alleviating irritation during drip (Patent document 10).